Clock-synchronizing mechanism



Aug. 6, 1929.

3 Sheets-Sheet l R. M. WOOD 1,723,964 CLOCK SYNGHRCNIZING MECHANISM Filed May 29, 1 9

Aug. 6, 1929. R WQQD 1,723,964

CLOCK SYNbHRONIZING MECHANISM Filed May 29. 1925 3 Sheets-Sheet 2 v gvwenfo;

Aug. 6, 1929. R M. wool:

CLOCK SYNCHRONIZING MECHANISM Filed May 29, 1925 5 Sheets-Sheet 3 atto'umq Patented Aug. 6, 1929.

UNITED STATES RUSSELL a. wool), or rmmrmrn, new JERSEY, ssrenoa '10 RADIO nrncrnrc 1,723,964 PATENT OFFICE.

, CLOCK CORPORATION, 01 NEW YORK, N. Y., A CORPORATION OF. DELAWARE.

CL OCK-SYNCHRONIZING MECHANISM.

Application filed May 29, 1925. Serial m, 33,820.

The present invention relates to clocksynchronizing mechanism, and relates more particularly to apparatus of'this character adapted to be utilized in correcting master or other clocks by Hertzian waves transmitted thru' space from a .central station at which a standard time piece islocated.

The present invention comprises an improvement over the invention disclosed in lo the application of T.- S'. Casner, Serial No: 748,271, filed Nov. 6, 1924, and is adapted to be used in connection with a synchronizing system such as therein disclosed. The application referred to discloses a system in m which radio time signals,v such as those sent out from the United- States Government sta- 2: closed periodically by the clock mechanism,

a clock controlled time switch which is adapted to be closed shortly before the time signals are due to be transmitted to put the entire system inoperative condition, clock correcting mechanism which is adapted to' set the hands of the clock when, current is passed thru the same, and an electromagnetic switching device connected to the relay and the pendulum contacts and adapted to, select the proper; signal from the groups of impulses sent out so as to close the circuit of the clock correcting mechanism at the proper instant.

The primary aim of this invention, is to provide an additional safeguard for this electromagnetic switching device which will I prevent the clock correcting circuit "from being closed at the wrong instant. More specifically, in the Gasner application above referred to, an accidental break in the signals equalling or erceeding the correct length of one of the silent periods of the code of time signals, would cause the clock to be set erroneously by the next succeeding signal. This invention has for its purpose to provide a means whereby the clock correctin circuit may be closed only by a signal to lowing a silent period of exactly the correct duration, and which therefore great- :15 ly diminishes the possibility of error.

and

Further objects and advantages of my invention will be apparent from the following description, taken in conjunction with the accompanying drawings, which form, apart of this specification, and in which;

Figure 1 is a front elevation of an electromagnetic switching device embodying the present invention;

Figure 2 is a rear elevation of the same;

Figure 3 a diagrammatic view showing the electrical connections of the invention 1n relation to the other parts of the synchronizing system.

Referring more particularl to the drawings, in which like reference characters denote like parts throughout the several views thereof, denotes a vertical support" or panel which isv secured to a suitable base 11. A toothed wheel 12 is rot-atably mount ed on a stud 13 secured to the face of the panel 10 near the top thereof. The wheel 12 in the present instance is provided with SIX efi'ective teeth 14 arranged along a portion of its periphery. such as a spring 15 tends to keep the wheel constantly in the posit-ion shown in Figure 1 with a shoulder 16 on the wheel contacts mg with a stop pin 17 mounted on the panel. 1

Means are provided to impart a step step movement to the wheel, and comprlse.

a pawl 18 pivoted at its lower end to one arm of a right angled armature 19 pivoted at its apex to the panel 10. "The armature 19 is adapted to be moved about itspivot against the action of a spring 20 and a dash pct 21 by a pair ofelectromagnets 22 and is, normally held retracted from the poles'of the electromagnets 22 by the spring 20. A dog 23 is urged to engage the teeth of wheel 12 bymeans of a spring 24 and is adapted to hold the wheel in advanced position.

An armature 25 is pivoted at 26 to the vertical panel 10 and 1s adapted to be ops erated by an electromagnet 27. The armature 25 is provided with a projection or knob 28 which engages the pawl 18 and holds it and the do 23 out of engagement with the teeth 14 when the electromagnet 27 is deenergized, as shown in Fi ure 1. An in- A biasin means sulating rod 29 connects the armature-25 with a leaf spring blade 30-which is secured to an insulating block 31 mounted on the ill] k with a shoulder 40 adapted to engage the panel 10, and which holds the armature 25 in the retracted position shown in Figure 1. As indicated on the drawing, the rod 29 may be supported by having reduced ends thereof engaging respectively apertures in spring blade 30 and armature 25. The free.

30. The spring 34 is provided with abe'nd,

or hump 36, the

purpose of which will appear hereafter.

An arm or sector 37 of insulating material is also rotatably mounted on the shaft 13 independently of the wheel 12, and is connected to the wheel 12 by means of a pin 38 on the wheel which passes thru an arcuate slot 39 in the sector. Sector 37 is formed bowed portion or hump 36 of spring "blade .34. The circumferential length of slot 39 is such that the wheel 12 can be rotated from its initial position thru an angle subtended by four teeth without affecting sector, 37. On further rotation of wheel 12, however,.as when it has been advanced five teetln pin 38 contacts with the lower end of the slot 39 so that the wheel 12 and the sector 37 move together, the shoulder 40 of the sector pressing spring 34 to the right from the position shown in Figure 1. When the spring 34 has been thus pressed to the right the contact 35' will engage the contact 32 on spring 30 when the magnet 27 is deenergized so that the spring 30*'-'1s in the position shown in Figure 1. The contacts 32 and 35 will not engage until each has been moved towards the other. It is obvious, of course, that instead of using a single switch having two movable terminals, two switches connected in series might be employed, each switch having one movable terminal cooperating with a stationary terminal.

As will be seen in Figure 2, a ratchet wheel 41 is rotatably mounted on the rear of panel 10 and is adapted to be operated by a pawl 42. This pawl is operatively connected to the armature 25, the connection chosen consisting in a pin 43 fixed to the armature and projecting thru a slot 44 in the panel and having its projecting end pivoted to pawl 42. Pin 43 also passes thru a vertical slot 45 in an arm 46 pivoted at 47 and having its free end connected to the piston of a dash pot 48. a

Rachet wheel 41 has one or more of its teeth omitted at 49, so that after it has been stepped around to the point where this mutilated part is under pawl-42, further operation of the latter effects no rotation of the wheel. When this point is reached a pin 50 on wheel 41 rests in a notch on the peak ,inside edges of these of a cam 51 secured to the back of a spring blade 52 provided with a contact 53 at lltS free end, and by thus flexing the blade to the left from the position shown in Figure 2, presses this contact into engagement with a similar contact,54 secured to a second spring blade 55. The spring'blades 52 and 55 are each mount d' at their lower ends on an insulating block 56. An electromagnet 57 has its pole pieces 58 projecting respectively above and below wheel 41 so as to cooperate with an armature 59 secured in any suitable way to the wheel 41. Wheel 41 in armature 59 may be mounted so as to be frictionally 'held against retrograde movement. When the wheel 41 has been rotatedto the point where pawl 42 is over the mutilated part of the wheel and pin '50 rests on the peak of cam 51, the parts will remain in such positions until magnet 57 is energized, whereupon armature 59 will be drawn to the vertical position shown in Figure 2, thereby rotating wheel 41 sufliciently to bring the next ratchet tooth thereof into engagement with pawl 42 and to cause pin 50 to clear cam 51, allowing contacts 53 and 54 to separate. Pawl 42 is then effective to step the ratchet wheel around when operated until the mutilated part 49 againcomes under the pawl. The wheel 41 may be providedwith any suitable number of teeth, the number adopted in the present instance being 22.

The parts so far disclosed are shown in the applicationreferred to above and I now come to a description of the present invention. Referring to Figure 1, a switch arm 60 is pivoted to a stud 61 secured to an insulating block 62 fastened of the panel 10. The arm 60 has at its lower end two prongs 63, the angle between the prongs being equal to that subtended by five teeth on the wheel 12. The upper end of the arm 60 is adapted to make contact with a projecting contact 64 extending from a flat contact piece 65 secured to the block 62. A pin 66 is secured to the wheel 12 in such position as .to be in contact with the left hand prong 63 when the parts are in the position shown in Figure 1.

The wiring of the apparatus is shown in Figure 3 in diagrammatic form. 'A radio receiving set of any suitable construction is indicated at 70 and a battery for energizing the set at 71. Battery 71 is also uti- 'lized for operating electromagnets 22 and 27. The receiving set should be sharply tuned to the frequency of the time signal waves. An audio frequency relay of any suitable construction is illustrated diagrammatically at 72. When the set is rendered operative relay 72 will be energized .upon the reception of each signal impulse and will be deenergizedat all other times. A pair of contacts 73, 74 are operated by the relay near the top by the reception of a signal impulse. 75 denotes the pendulum of a suitable master clock which carries a pair of movable contacts 76 adapted to engage with a pair of stationary contacts 77 so as to close the circuit between these contacts once each second.

78 represents a clock controlled switch, the details of construction of which may be found in the application referred to above.

" nal-responsive' circuit.

This switch is operated by the clock in such manner that the contacts 79 and 80 thereof will be closed at approximately five minutes to noon each day. Suitable -mechanism is provided for opening these contacts immediately following correction of the clock by the clock correcting mechanism, or, failing this, the contacts 79 and 80 will be opened by the clock itself at half minute after noon.

Normally the radio receiving set 70 is in operative and is rendered operative only during the time that the contacts79 and 80 are closed, at which time battery 71 is connected to the receiving set by a circuit including conductors 81, 82, 83, contacts 79 and 80 and conductor 84 back to the battery. For convenience of description I will call this c ircuit the receiving-set-energizing circuit.

The circuit of electromagnet 27 may be traced as follows: conductor 81 from one side of the magnet to one side of the'batte'ry,

approximately oneconductor 84 from the other side of the battery to switch 78, conductors 83 and 85 to contact 73 of relay 72, and from contact 74 of the relay to the other side of electromagnet 27 by conductor 86. Since this circuitis opened upon the reception of each time signal, it may be called the time-sig- The circuit of electromagnets 22 includes conductor 87 to contact 54, thence to'contact 53, conductors 88 and 81 to' battery 71, the other side of battery 71 to pendulum contacts 76 and 77, and conductor 96 from contacts 77 back to electromagnets 22. As this circuit is controlled by the clock so as to be closed and opened at one second intervals after the preliminary closure of contacts 53-and 54, it may be called the Fclockcontrolled circuit.

Finally, the circuit of electromagnet 57 includes conductor 89 to switch arm 60, ,con-

' tact 64, conductor 90, contacts and 32,

conductor 91 andbattery 92. The other side of'electromagnet 57 and battery 92 are to be connected by'conductors 93 and 94 respectively to the terminals ofthe clock correcting mechanism 95. A suitable mechanism for this purpose is shown in the Casner application referred to above. Since the armature'59 resets the. premature-opera-. tion-preventing switch 53, 54, this circuit may be called the clock-correcting and switch-resetting circuit.

The time signals transmitted from the A1- lingto'n station begin at five minutes before noon and are sent out in a series of impulses of very short duration, called for convenience dots, one every second, omitting the thirtieth second of each minute, up to and including the fifty-fifth second of the fifty-sixth, fifty-seventh, fifty-eighth and fifty-ninth minute, and a like series of dots up to and including the fiftieth second of the sixtieth minute, there being a single long impulse sent out beginning exactly at noon. That is to say, for five minutes just preceding noon, short signal impulses are being sent out at one second intervals, omitting the thirtieth second of each minute, except during the five seconds at the end of the fiftysixth, fifty-seventh, fifty-eighth and fiftyninth minutes, and except during the ten seconds preceding noon. The apparatus acordinarily vary more than a few seconds from the correct time, it may be assumed that the switch 78 will be closed at or within a few seconds of five minutes before noon. \Vhen the switch 78 closes, battery 71 is connected to the radio receiving set thru the receiving-setenergizing circuit, thereby rendering the set operative, and magnet 27 is also connected to the battery 71 thru the time-signal-responsive circuit. Magnet 27 will accordingly be energized,-attra ct ing its armature 25 and permitting pawl 18 and dog 23 to come into engagement with ratchet wheel 12 and also rotating ratchet wheel 41 thru an angle of one tooth. Now upon the reception of the first dot subsequent to the closure of switch 78, relay 72 will be energized, thereby opening the circuit of magnet 27. The armature 25 willthereupon be retracted by spring 30, throwing pawl 18 and dog 23 out of engagement with the wheel 12 and retracting pawl-42 into position to engage the next tooth of ratchet wheel 41. Upon cessation of the dot the circuit of magnet 27 will be again closed, permitting pawl 18 and dog 23 to engage the wheel 12 and advancing ratchet wh'eel 41 another tooth. Thus wheel 41 will be stepped around one tooth per second during the initial part of the signal reception, or until the mutilated part 49 of the wheel has been brought under the pawl 42. As the-wheel 41 has 22 teeth, thls number of operating impulses of pawl 42 is required to step wheel 41 from its initial position to the position 51 and closes contacts 53, 54. Since'pawl 42 is given an operating impulse upon the reception of each dot, it follows that contacts 53, 54 will be closed approximately on the twenty-second second of the fifty-sixth minute of the hour preceding noon. If the clock is fast, so that the switch 7 8' is closed prior to the beginning of the time signals, contacts 53, 54 will be closed exactly on this twenty-second second. If the clock is slow, so that switch 78 is closed subsequent to the beginning of the time signals, contacts 53, 54 will be closed a corresponding interval after this twenty-second second.v Within rather wide limits the exact time of closure of contacts 53,-54isimmaterial; 1

The closing of contacts 53,54 closes one of the g'aps in the clock-controlled circuit,

the other gap in this circuit being at the penduluni contacts 76, 77b It w'ill be evident that the electromagnets 22 will be energized and deenergized once each second by the closing of the pendulum contacts 76, 77 after the contacts 53, 54 are closed as above described. Upon each' energization of magnets 22, pawl 18 will be. raised, but unless magnet 27 is simultaneously energized'the pawl will be held away from the teeth. ofwheel '12 by the knob 28 on armature 25. If the signal impulses are synchronous with the energizations of magnets 22, so thatmagnet. 27 is deenergized when magnets22 are energized,

pawl 18. will be held away from wheel 12 and the latter will remain'unatfec'ted as long as the signals come once per second. If the signal impulses are not synchronous with the energizations of magnets 22, magnets 22 and 27 may be simultaneously energized,-in'

which event pawl 18 will step wheel 12 thru an angle of one tooth but the wheel will be immediately returned to its initial position upon reception of the next signal impulse and consequent deenergization of magnet 27. It therefore follows that under no circumstances can the wheel 12 be operated thru an angle exceeding that subtendedby one tooth so long as the signal impulses come in once per second.

During the five-second silent period just preceding the beginning of the fifty-seventh minute, relay 72 is deenergized, closing the time-signal responsive circuit and energizing magnet 27 during the whole'of this period. Hence pawl 18 and dog 23 will be in their operative positions with respect to wheel 12 for five seconds, ermittingmagnets 22 to step wheel 12 tiiru an angle of five teeth. At the fourth step pin 38 reaches the bottom of slot 39, and on the fifth step sector 37 is moved downwardly, its shoulder .40 pressing spring blade 34 to the right.

Now upon reception of the impulse at the end of the'sixtieth second, or thebeginning of the fifty-seventh minute, relay 72will 'be energized, opening the time-signal-responsive circuit thru magnet 27 This will permit spring blade 30 to move tothe left, and contact 32 will engage contact 35, thereby closing the clock-correcting-andswitch-resetting circuit thru magnet 57 and the clock correcting mechanism connected to conductors 93 and 94. The second hand of the clock will thereby be set in a vertical or zero position, if it is not already in that position, as described in the Casner application referred to above. The contacts 79, 80 will be simultaneously opened as fully set forth in Patent 1,575,096 to Casner, thereby disconnectingbattery 71 and putting the apparatusin aninoperative condition until five minutes preceding noon of the next day. When the magnet 27 is deenergized upon the reception of the impulse at the beginning of the fifty-seventh minute, as described, pawl 18 and dog 23 are removed from engagement with wheel 12, permitting spring 15 to rotate the wheel to its initial position with its shoulder 16 engaging stop pin In returning to this position, pin 38 on the wheel engages the upper end of slot 39 in sector 37 .and moves the second hand of the clock. It will be observed that the deenergization of magnet 27 eifects both the closing and the opening of the circuit. thru the clock correcting mechanism', so that the latter is energized only an instant, thereby offering no'appreciable interference with the operation of the second hand. -The parts are so constructed that the switch blade 30 is-brought into engagement withlblade 34 before dog 23 is removed'from engagement {with the teeth of jwheel12, thus permitting the clock correcting mechanism to be energized lon enough to overcome its electrical inertia an the mechanical inertia of the parts operated thereby. The energization of magnet 57 when. the cIock-correctin and-switchresetting circuit is closed, as. escribed, will turn armature 59 to its vertical position,

thereby rotating ratchet wheel 41 thru a sufiicient angle ,to cause the opening of contacts' 53, 54 and the engagement of pawl 42- with a ratchet tooth. Thus battery 71- is disconnected and all the various parts of the apparatus are returned to their normal positions automatically upon completion of the setting operation. i

It will be noted that the operation of wheel-41 thru a. predetermined number of steps must be performed. before magnets 22 can be energized to step'around wheel 12 and effect the setting of the clock. The

purpose of thus making the operation of wheel 41 a condition precedent to the setting of the clock is to insure that the time signals are actually being received and that the apparatus -is properly responsive, and hence that the clock will not be set prematurely and inaccurately. It is possible that due to the fact that the clock is fast, relay 72 would not attract its armature until five seconds or more had elapsed after the closing of switch 78: In such an event, if the circuit of magnets 22 were controlled solely by the pendulum'contacts 76, 77, magnets 22 would step wheel 12 around five steps before relay 72 had responded to a time signal, and the clock would be wrongly set on the first response of relay 72. 71th the circuit of magnets 22 controlled by contacts 53, 54, an inaccurate setting from such cause.

cannot occur, as these contacts are closed only after the reception of a predetermined number of time signals. 1 a It may happen that during the five-secon silent period preceding the beginning of the fifty-seventh minute, relay -72 will be energized by the response of the receiving set to a stray signal or static. If this should happen, magnet 27 would be deenergized and its armature would throw pawl 18 'and dog 23 out of engagement with wheel 12, which would then return to its initialposition, pre venting setting of the clock at the end of this silent period. But in the absence of interference the clock would be set at the end of the next silent period or at the .beginning of the fifty-eighth minute. That is to. say, the clock ma be set at the end of any one of the four ve-second silent pe- Iiods preceding noon, so that if interference occurs in the first silent period, the clock setting will take place at the end of the first succeeding silent period during which no interference occurs. 'In the improbable event that there'is interference during all the silent periods, failure to set the clock will, of course, occur, and the apparatus will remain in the operative conditlon until approximately one-half minute after noon, when the switch '78 will be opened by the operation of the clock.

Ashas been stated above, the'angle between the inside edges of the prongs 63 of arm-60 is equal to the angle subtended by five teeth on the wheel 12. It will thus be seen that no movement of the arm 60- will take place during a silent period of only five seconds. If the signals should, however, be accidentally interrupted for any reason, the

' sixth step of the wheel 12 will cause the pin thereby be opened, preventing the next signal received from setting the clock erroneously, as would otherwise be the case. \Vithout this additional safeguard, any accidental interruption of the signals, causing asilent period exceeding five seconds in du ration, would result in the clock being set erroneously by the next impulse received. This additional safeguard renders it impossible to use the final ten-second silent period for setting the clock, as may be done with the original Casner construction, but this is not a serious loss as it is exceedingly improbable that the clock will fail to be set during one of thefour preceding five-second n It is to be understood that'although the present invention has been specifically described in connection with. a code of time signals transmitted by radio, it is by no means limited thereto. The invention may be applied to the selection of a desired signal from a code of signals however trans mitted, and may be'utilized either to set a clock or to give any other indication of the instant. of receipt of said signal.

It will be apparent to one skilled in the art that various changes, or modifications might be made in my invention without affecting the spirit thereof, and I desire to be limited, therefore, only by the prior art and the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is as follows:

1. In .a system for setting a clock in response-to a code of time signals,'switching mechanism for controlling an electric circuit through a clock correcting mechanism, comprising in combination, means tending to close said circuit upon receipt of each signal, means tending to close said circuit after a silent, period of certain definite duration, and means for opening said circuit after a silent period exceeding, said certain definite duration, whereby said clock correcting mechanism may be actuated only bya silent eriod of said certain definite length immediately followed by a signal.

,2. In a system for setting a clock in response to a code of time signals, means for controlling an electric circuit through a clock correcting mechanism, comprising in combination, a switch in said-circuit consisting of two normally-separated movable terminals, means for moving one terminal towards the other upon receipt of each signal and for moving it away upon the cessation thereof, means for moving the other terminal towards the first terminal after a said terminals being adapted to contact only when each has been moved towards theother, a second switch in said circuit consisting of two normally engaged contacts, and means for opening saidsecond switch after a silent period exceedingsaid certain definite duration, whereby both of said switches may be closed and said clock correcting mechanism actuated only by a silent period of said certain definite le" gth immediately followed by a signal.

3. In a system for setting, a clock in response to a code of time signals, means for controlling an electric circuit through a clock correcting mechanism, comprising in combination, a switch in said circuit consisting. of two normally separated movable terminals, means for moving one terminal towards the other upon receipt of each signal and for moving it away upon the cessation thereof, clock controlled step-by-step mechanism adapted to move the other terminal towards the first terminal when moved a predetermined number of steps from an initial position, said terminals being adapted to contact; only when eachv has been moved towards the other,-m eans to return thestep-by-step mechanism to its initial position upon receipt ofeach signal, a second normally closed switch insaid circuit, and means for opening said switch when said step-by-step mechanism 1 has moved more than said predetermined number of steps necessary to move said second terminal. a i

4. In a system for setting a, clock in re.- sponse to a code of time signals consisting of a; plurality of series of impulses separated by silent periods, in combination, clock controlled step-by-step mechanism, impulse responsive means for returning said mechanism to initial position upon reception of each impulse, whereby said \mechanism will operate through a certain phase only during one of said silent periods, electromagnetic clock setting means having a circuit controlled jointly by said mechanism andsaid means and closed only'when an impulse is received at the completion by said mechanism of said phase. of movement, and means controlled by said mechanism for opening said circuit whenever the a movement of said mechanism exceeds said phase.

5 In a system for setting-a clock in rei phase of movement only during one of said silent periods. means fofsetting the clock controlled jointly by said mechanism and said means and actuated only when an impulse is received at the completion of said phase of movement by said mechanism, and

means controlled by said mechanism for a rendering said clock setting'means inoperative whenever the movement of said mechanism exceeds saidtphase.

In testimony whereof I hereunto a fix my signature.

R ssnLL M. woon. 

